This content originally appeared on DEV Community and was authored by Vivesh
Ansible is a powerful open-source automation tool that simplifies IT tasks like configuration management, application deployment, and orchestration. It allows you to automate repetitive tasks, manage infrastructure as code, and ensure consistency across your environments. If you're new to Ansible, this guide will help you get started with an introduction and a basic example.
What is Ansible?
Ansible is a tool that automates tasks across multiple systems. It uses a simple language called YAML (Yet Another Markup Language) to describe how a system should be configured or what tasks should be run. The key features of Ansible include:
- Agentless: Unlike other automation tools, Ansible doesn’t require any agents installed on the target machines. It uses SSH to connect to them, which makes it easy to set up.
- Declarative Language: You describe the desired state of your systems in playbooks, and Ansible takes care of achieving that state.
- Idempotency: Running a playbook multiple times won’t cause issues; Ansible ensures that the end state is always the same.
Setting Up Ansible
Before we start with examples, let’s set up Ansible on your local machine.
Step 1: Install Ansible
Ansible can be installed using pip (Python package manager) or from your system's package manager.
For Ubuntu/Debian-based systems:
sudo apt update
sudo apt install ansible -y
For CentOS/RHEL-based systems:
sudo yum install epel-release -y
sudo yum install ansible -y
Using pip:
pip install ansible
To confirm the installation, run:
ansible --version
Step 2: Set Up SSH Access to Remote Machines
Ansible communicates over SSH. You should be able to SSH into your remote machines without a password prompt using SSH keys. You can set up SSH keys using:
ssh-keygen -t rsa
ssh-copy-id user@remote_host
Replace user and remote_host with your remote machine’s username and IP address.
Ansible Concepts
Before diving into examples, let’s understand some basic terms:
- Inventory: A file that defines the list of servers Ansible will manage.
- Playbook: A YAML file that contains tasks for Ansible to execute.
- Task: A single unit of work, like installing a package or copying a file.
-
Module: Ansible uses modules to execute tasks (e.g.,
yum,apt,copy,file).
Example 1: Creating a Simple Playbook
Let's create a basic playbook to install the Apache web server on a remote host.
- Define the Inventory File
Create a file called hosts.ini and specify the IP addresses or hostnames of the servers you want to manage:
[webservers]
192.168.1.10
- Write the Playbook
Create a file named install_apache.yml:
---
- name: Install Apache on web servers
hosts: webservers
become: yes
tasks:
- name: Ensure Apache is installed
apt:
name: apache2
state: present
when: ansible_os_family == "Debian"
- name: Ensure Apache is installed (CentOS/RedHat)
yum:
name: httpd
state: present
when: ansible_os_family == "RedHat"
- name: Start and enable Apache service
service:
name: "{{ ansible_os_family == 'Debian' | ternary('apache2', 'httpd') }}"
state: started
enabled: true
Here’s what this playbook does:
-
name: Describes the playbook action. -
hosts: Specifies which servers will run the playbook. -
become: yes: Tells Ansible to usesudoto run tasks. -
tasks: Contains the actions (installing packages, starting services). -
when: Conditional statements to handle different operating systems.
- Run the Playbook
To run the playbook, execute:
ansible-playbook -i hosts.ini install_apache.yml
Ansible will SSH into the servers listed under [webservers] in hosts.ini, install Apache, and ensure the service is running.
Example 2: Create a Simple File Using Ansible
Suppose you want to create a file on a remote server using Ansible. You can use the file module for that.
- Playbook to Create a File
Create a new file create_file.yml:
---
- name: Create a file on remote servers
hosts: webservers
become: yes
tasks:
- name: Create a file named "info.txt"
file:
path: /tmp/info.txt
state: touch
owner: root
mode: '0644'
This will create a new file /tmp/info.txt on the remote machine with the specified permissions.
- Run the Playbook
Run it using:
ansible-playbook -i hosts.ini create_file.yml
Tips for Beginners
- Start Simple: Begin with basic tasks like installing packages or managing services before moving on to complex playbooks.
- Modular Approach: Reuse tasks across multiple playbooks by writing roles.
- Learn YAML: Understanding YAML syntax is essential for writing effective playbooks.
-
Use Dry Runs: Test playbooks without making changes using the
--checkoption:
ansible-playbook -i hosts.ini install_apache.yml --check
Happy Automating!
This content originally appeared on DEV Community and was authored by Vivesh
Vivesh | Sciencx (2024-10-28T15:34:28+00:00) Getting Started with Ansible: A Beginner’s Guide. Retrieved from https://www.scien.cx/2024/10/28/getting-started-with-ansible-a-beginners-guide/
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